High-Performance Ceramics III

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Authors: Mao Qiang Li, Xue Feng Chen
Abstract: Ceramic discs are prepared with PZT powder doped with Sr and Mn, which is prepared through a modified Pechini process. A micro-actuator consists of two concentric rings with thickness of 0.15 mm made of PZT doped with Sr and Mn, a copper disc, on which the PZT rings are firmly mounted with organic glue, and a ceramic rod of φ2.5x100 mm stuck at the center of the disc. The top of the ceramic rod serves as pointer of the actuator. The outer PZT ring is equally divided into four quadrants separated each other, of which two vicinal parts are poled with the same direction as that of the inner PZT ring. The other two quadrants in the outer ring are poled with the opposite direction. The inner ring and the four quadrants of the outer ring are excited by three DC powers, respectively. Bending deformation of the copper disc is caused by properly regulating the excitation voltages exerted on the PZT ceramics. The position of the top of the ceramic rod varies with the bending deformation of the copper disc.
195
Authors: Bao Shan Li, Guo Rong Li, Zhi Gang Zhu, Wang Zhong Zhang, Qing Rui Yin, Ai Li Ding
Abstract: This paper aims at the determination of the effects of strontium addition on the microstructural evolution and the piezoelectric properties for Pb(Mn1/3Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) ceramics. The Sr content was chosen in the range of 2-8 mol%. These materials were prepared by the solid phase reaction of the oxides. It was found, from the experimental results, the tetragonality of the PMnN-PZT lattice and the Curie temperature decreased with Sr content; in the meantime, dielectric constant increased greatly. Dielectric constant (er) and planar coupling factor (Kp) was proven to be dependent on sintering temperature. P-E curves of PMnN-PZT system exhibited some “pinched” shape instead of the normal square-like P-E loops, illustrating presence of the oxygen vacancies by reason of the preferable substitution of the B-sites ion.
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Authors: Li Feng Wang, Qingchi Sun
Abstract: Piezoelectric Pb(Sn1/3Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-PbTiO3-PbZrO3 (PSZN-PZT) quarternary ceramics with varying Zr/Ti ratio, which locate in the vicinity of the morphotropic phase boundary (MPB), were prepared by the conventional calcination route. The conventional and twice synthesis methods were compared. XRD patterns indicated the more complete perovskite phase was formed by the twice synthesis methods. The sintering behavior was investigated. The microstructure was studied and the piezoelectric and ferroelectric properties and the properties under high electric field were determined. The optimized results were obtained when the ratio of Zr/Ti is 43/45 and the sintering temperature is 1260°C.
205
Authors: Hui Shi, Wei Pan, Ming Hao Fang, Dan Xie
Abstract: Bismuth sodium titanate ceramic was prepared by sol-gel method. The crystallization, density and microstructure were determined. The grains of BNT ceramic prepared by sol-gel method were equiaxial, ~ 2 µm, which was smaller than that prepared by solid-state reaction method. The piezoelectric and dielectric properties were investigated. When the sintering temperature was 1140°C, maximum relative dielectric constant and piezoelectric constant can be obtained. The piezoelectric constant of BNT ceramic prepared by sol-gel method was higher than those prepared by solid-state reaction method.
209
Authors: Hua Zhou, Qingchi Sun, Cuimin Lu
Abstract: Praseodymium (Pr) modified lead zirconate titanate ceramics (Pb1-1.5xPrx (ZryTi1-y) O3 with x = 0.02, 0.04, 0.06, 0.08 and y = 0.51, 0.52, 0.54, 0.56, 0.58, 0.60) were prepared by the high temperature solid-state reaction method. X-ray diffraction (XRD) results show that the morphotropic phase boundary (MPB) of Pb0.955Pr0.03(ZryTi1-y)O3 (PPZT1) is located in the area where the molar fraction of Zr is near 55%, when the molar fraction of Zr is 54% and the sintering temperature is 1240°C with 1h curing time, the superior piezoelectric properties of compositions of PPZT1 system were optimized, a set of d33 = 420 pC/N; eT 33/e0 = 2,000; Tc = 314°C; Qm = 76; tand = 2% and kp = 0.53. On the other hand, Pb1-1.5xPrx(Zr0.54Ti0.46)O3 (PPZT2) is far from MPB and their compositions are all in tetragonal phase.
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Authors: Zhi Gang Zhu, Bao Shan Li, Guo Rong Li, Qing Rui Yin
Abstract: The effects of SiO2 additives on microstructure, piezoelectric and mechanical properties were investigated for Pb0.98Sr0.02(Mn1/3Sb2/3)0.05Zro.48Ti0.47O3 (PMS-PZT) ternary system close to the morphotropic phase boundary. Piezoelectric coefficient (d33) and electromechanical coupling factor (Kp) considerably deteriorated with the substitution of SiO2 increased. On the other hand, the mechanical quality factor (Qm) increased, the maximum value was 1800. Fracture strength of 1.0 wt% SiO2 added the specimens reached to 106.54 MPa which was about 1.4 times higher than pure PMS-PZT ceramic. The rapid improvement of fracture strength probably due to the decrease of grain size, pore distribute and the second phase (redundant Si4+ ions) segregating on the grain boundary which enhanced the bond energy of grain boundary. The optimized concentration of SiO2 doped PMS-PZT ceramics was 0.4 wt% for high power application: d33 = 300 PC/N, Kp = 0.51, Qm = 1500, tand = 0.32% and the fracture strength was 88.5MPa.
215
Authors: Hua Jun Sun, Wen Chen, Qing Xu, Jing Zhou, Xiao Fang Liu
Abstract: Using Zr(NO3)4.5H2O as Zr source, PZT powder with a single-phase perovskite structure was synthesized by a sol-autocombustion method at a calcining temperature of 700°C. Compared with a solid-state reaction method, the calcining temperature of PZT can be lowered by 200°C when using the sol-autocombustion method. PMZN ceramic was prepared at a sintering temperature of 1050°C with the resulting PZT powder as a base, which can lower the sintering temperature by 150°C. The microstructure of the PMZN ceramic was investigated by XRD and SEM, and the dielectric and piezoelectric properties were measured. The results showed that the PMZN piezoelectric ceramic has a tetragonal perovskite structure, showing the main electrical properties as follows: Kp = 0.54, Qm = 1073, tgd £ 0.001, e33 T/ e0 = 1236, d33 = 454pC/N, and fs =136.1KHz.
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Authors: Jin Song Pan, Xiao Wen Zhang, Ke Pi Chen, Chao Lei
Abstract: (1-x)(0.64PNN-0.36PT)-x(0.91PZN-0.09PT) ferroelectric ceramics with different x were synthesized by the columbite precursor method. The phase structure and piezoelectric properties were investigated. XRD profiles implied that with the increasing of x, samples could no longer maintain the pure perovskite phase. All the compositions were found to lie within the region of the morphotropic phase boundaries (MPBs) with different contents of rhombohedral and tetragonal phases. The piezoelectric coefficients for compositions with x £ 0.30 were obviously better than those for the rest ones and the composition with x = 0.15 exhibited the largest value of d33 among all the samples. The relationship between the structure and the piezoelectric properties was discussed.
223
Authors: X. Zeng, Ai Li Ding, X.S. Zheng, Yong Zhang, Ping Sun Qiu
Abstract: La-modified PZN-PZT compositions with representative formula Pb1-0.7xLa0.7x(Zn1/3Nb2/3)0.3- (Zr0.55Ti0.45)0.7(1-x/4)O3 were prepared by the columbite precursor method. La content, x, was varied from 0 to 8mol%. Effects of La doping on microstructure, dielectric and piezoelectric properties were investigated. The results showed that in present system La doping promotes the formation of pyrochlore phase and the phase shifted from rhombohedral to tetragonal structure with increasing La content. It was also found that La doping makes dielectric permittivity maximum decrease and the degree of diffuse phase transition enhance. Appropriate amount of La doping could improve the piezoelectric properties.
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Authors: Xi Yun He, Ai Li Ding, Yong Zhang, Zi Ping Cao, Ping Sun Qiu
Abstract: PLZT (9/65/35) thin films on sapphire (001) substrates with thickness of 0.1 ~ 0.9 µm were prepared by a metal-organic decomposition (MOD) process. All the films present highly (110)-preferred orientation independent of the film thickness. The microstructure of the films was investigated. The influence of film thickness on optical properties of PLZT films was examined and analyzed. As the film thickness is increased, the absorption edge of the film is shifted to longer wavelength; the optical band gap Eg is increased slightly. The refractive index at 510nm determined from optical transmission spectra also shows an increasing tendency as film thickness increasing. Great stress aggregated during the film preparing process is thought to be an important reason which results in the variations of optical properties of the films with different thickness.
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